Method and system for determining source signatures after source ghost removal

Patent metadata

Field	Value
Publication number	US-9411062-B2
Application number	US-201213367787-A
Country	US
Kind code	B2
Filing date	Feb 7, 2012
Priority date	Feb 7, 2012
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

Seismic data are acquired using a seismic source comprising a plurality of seismic sub-sources disposed in a body of water at a plurality of depths and activated with different time delays. Far-field signatures are determined for the plurality of seismic sub-sources at each of the plurality of depths. A composite ghost-free far-field signature of the seismic source is determined from the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths and different time delays. A source response is removed from the seismic data using the far-field signatures of the seismic source.

First claim

We claim:

1. A method for mapping the earth's geology, comprising:
obtaining seismic data acquired using a seismic source comprising a plurality of seismic sub-sources disposed in a body of water at a plurality of depths and activated with different time delays;
determining far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths;
determining a composite ghost-free far-field signature of the seismic source from the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths and different time delays; and
removing a source response from the seismic data using the composite ghost-free far-field signature of the seismic source.

2. The method of claim 1 , wherein the determining far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths comprises:
determining notional source signatures for the plurality of seismic sub-sources at each of the plurality of depths; and
determining a far-field signature from a weighted summation of the notional source signatures.

3. The method of claim 1 , wherein the determining far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths comprises:
measuring the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths.

4. The method of claim 1 , wherein the determining far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths comprises:
modeling the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths.

5. The method of claim 1 , wherein the removing the source response from the seismic data comprises:
applying a weighted summation to the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths and different time delays.

6. The method of claim 1 , wherein the determining far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths initially comprises:
removing a receiver ghost from the seismic data.

7. The method of claim 6 , wherein the removing the receiver ghost from the seismic data
comprises:
measuring pressure and vertical velocity components of the seismic data; and
separating up-going and down-going wavefields using a weighted summation of the
measured pressure and vertical velocity components.

8. The method of claim 6 , wherein the removing the receiver ghost from the seismic data comprises:
removing the receiver ghost using a specially designed receiver system.

9. The method of claim 1 further comprising removing a receiver ghost from the seismic data.

10. The method of claim 9 , wherein the removing the receiver ghost from the seismic data comprises:
measuring pressure and vertical velocity components of the seismic data; and
separating up-going and down-going wavefields using a weighted summation of the measured pressure and vertical velocity components.

Assignees

• Parkes Gregory Ernest
• Hegna Stian
• Pgs Geophysical As

Inventors

• Parkes Gregory Ernest
• Hegna Stian

Classifications

• G01V1/3861 Primary

  control of source arrays, e.g. for far field control · CPC title

• G01V2210/56

  De-ghosting; Reverberation compensation · CPC title

• G01V1/3808 Primary

  Seismic data acquisition, e.g. survey design · CPC title

• G01V1/364 Primary

  Seismic filtering (G01V1/37 takes precedence) · CPC title